Sound processor performs volume adjustment & audio mixing

However, audio SoCs, which comprise the core of car audio systems, are trending towards lower voltages following greater process miniaturization, reducing the size of audio signals that can be supported. This increases relative floor noise, requiring low noise, high fidelity analog volume after the SoC stage.

In pursuit of characteristics required for car audio, ROHM expanded on its lineup of sound processors (which have been well received with more than 120 million units shipped worldwide over the last 5 years) with the BD34602FS-M that was developed with a focus on sound quality by utilising proprietary sound quality design technology. Class-leading characteristics such as low 0.004% distortion and 3.1uVrms floor noise make it possible to extract the full data from sound sources, improving spatial representation (location of sound source and perceived distance). The result is improved car audio quality (which is experiencing increased demand), while promoting the adoption of high resolution sound sources and a reduction in cabin noise.

Key Features:

1. Achieves high fidelity audio by introducing sound quality design technology that optimizes proprietary parameters

The BD34602FS-M integrates newly developed original audio quality technology. Extracting the full data from audio sources by optimizing 28 unique parameters centered on circuit configuration and electrical characteristics that have been shown to have an effect on IC sound quality enables accurate spatial representation (perceived distance and location of sound source), and as a result has been well-received by car audio manufacturers.

2. Incorporates key audio characteristics

• Reduces IC midpoint bias circuit noise by approx. 20%
• Decreases noise generated low-frequency noise generated in the volume circuit by up to 10x
• Improving resolution (sound clarity) and spatial representation (perceived location and distance from sound) along with transient characteristics by adopting a layout that suppresses signal interference makes it possible to extract the full data from audio sources

3. Provides industry-leading performance

Leveraging expertise cultivated over many years and analog design technology in areas that cannot be reproduced in simulations allowed ROHM to develop automotive sound processors that achieve an industry-low 0.0004% distortion and floor noise of 3.1uVrms during volume attenuation.

4. Built-in mixing circuit integrates original popping noise reduction technology

An interrupt function (mixing) for both voice navigation and hands-free modes is built in.

Generally, when turning mixing ON/OFF unwanted popping noise may occur, but with ROHM’s original advanced switching technology these popping noises are minimized.